Apparatus for molding



Feb. 7, 1933. P. MAHn-:U

APPARATUS FOR yMOLDING Filed Dec. 6, 1930 /v vf NTO R 95m/ M40/F@Patented Feb. 7, 1233 PATENT oFFica PAUL MAHIEU, oF rARIs. FRANCEAPPARATUS non Momma Application led December 6, 1,930, Serial No.500,617, and in France December 7, 1929.

The present invention has for its object to provide an improvedapparatus for molding under pressure and is primarily characterized inthat the pressure of the fluid acting on the material to be molded isprogressive. s

This essential characteristic obviates the blow holes which generallyform in castings made under pressure, due to the fact that the aircontained in the mold has insufcient time to escape completely by thejoints of the mold or the vents. f

In the process according to the invention, When'the metal is admittedintothe mold, a small regulable pressure is exerted thereon tofacilitate merely 'its flow and a highl er pressure is not placedl onthe metal until this has suilicientlyrilled the mold. The cast.- y'

' ing taking placeat the beginning under a moderate pressure the aircontainedin the l 2o mold has the necessary time to escape completelythrough the vents. Subsequently the high pressure, which may be varied,produces all its advantages. i It makes the metal take up the smallestdetails of the moldand it coml pensates for shrinkage of the metal,which shrinkage is particularly noticeable in the case of thick parts. y.f

4The annexed figure shows by way of er: ample oneembodiment of apparatusfor car- 3o rying out the invention.

In this figure the Crucible v1 contains the metal 2 maintained in amolten state by the hearth 3. The upper opening of the cru-cible closedby a tight cover 4 forms a kind oi air 3 5 bell, damping outrapidvariations of pressure. The air 0r other uid under pressure' is admittedthrough the conduit .8, which is formed with an intake chamber 8 V Inthe Wall of crucible 1 is formed va si- 40 phon-shaped conduit 9conducting the metal to 'the union or nozzle 10 receiving the mold.

To obtain progressive increase in the pressure use is made of anexpansion or reducing device comprising an expansion chamber 17 closedby a diaphragm 18 which through the rod 19 controls lthe valve Q0'disposed at the outlet of thev conduit v8. .The pressure regu.

l'ating spring 20 is controlled by the lever 12 and it willbe seen thatprogressivelower-A ing of this lever causes progressive increase4 of thepressure in 17 and 15. On raising the lever 12 the finger 21 carried byitacts on a valve 22 establishing communication between 15'and 17 andthe atmosphere.

ting the metal to descend through the conf` duit 9 to the same level asthat in the Crucible. The mold may then be removed and the operationrecommenced It is pointed out that applicants device differs from thoseof the prior art in being substantially automatic. When the valve 2O isopened by a depression of the lever 12, the air enters the Crucibleunder an initial pressure and When this pressure rises to a Certainpoint the back pressure in the expansion chamber 17, is exerted on thediaphragml'S,

' which is pressed o'utWard against thev pressure of the spring andautomatically closes the valve 20, Ithus allowing the airunder moderateand initial pressure to act on the metal in the Crucible.

`under increase of pressure, is admitted.

When sufficient action 1s deemed to have taken place and an increaseThis increase of .pressure may be regulated through vthe operation ofthe lever.,

It is obvious that the meansdescribed above.

4 1. In a molding apparatus oi the character described, a Cruciblehaving a contracted outf i let leading to a mold, a. conduit connectedto the crucible for the admission of air under pressure, said 'conduitincluding an expan-.

sion chamber, an open port in said chamber leading to the Crucible, avalve seating port in said chamber for admitting pressure thereto,

a diaphragm mounted in said chamber opposite said second port, a valvein-'said second port, having a stem connected to said diaphragm andmeans mounted on the'outside of said chamber, and adapted to exertdeterminable vamounts of pressure on said diaphragm.

. 2. In a molding apparatus of the character descr'bed,'a cruciblehaving a contracted outpressure, havin letleading to a mold, a conduitconnectedV to the cr'ucible for the admission-of air under expansioncham er,` and having a manually operablevalve between said chambers tocontrol the-passage of air from the intake chami ber, and means in aWall of said expansion chamber for automatically closing said valve whena determined back pressure has' been built up in said expansion chamber.

In testimony whereof I alixmy signature.

an intake chamber-and anV

